Tanning or dressing hides, skins, or the like.



UNITED STATES PATENT OF ICE.

FRIEDRICH VALENT'INER, OF LE'IPSIO-PLAGWITZ, GERMANY.

TANNING OR DRESSING HIDES, SKINS, OR THE LIKE.

fsPIEGIFIGA'lION forming part of Letters Patent No. 682,825, dated September 1'7, 1901 Application filed November 27, 1900. Serial No. 37,875. (N0 specimens.)

To all whom it may concern:

Be it known that I, FRIEDRICH VALEN- TINER, a subject of the King of Saxony, residing at Leipsic-Plagwitz, in the Kingdom of Saxony, German Empire, have invented specification.

The tanning of animal hides and the like may be effected in various diiferent manners.- In the following description I disclose a method of preparing a fiuorinated chromium compound by means of which the tanning of hides and such like may be very quickly and perfectly effected.

My invention can with advantage be carried out in the following manner: The fluorinated chromium hydroxid which I- prefer "to employ for the tanning process is preferably prepared as follows: One hundred kilograms sodium bichromate are dissolved in four times the quantity of water and mixed with five kilograms formalin, (forty per cent. aqueous solution of formaldehyde in water.) To this solution are added two hundred kilograms of ten per cent. hydrofluoric acid, and the whole is then heated at 60 to 70 centigrade until a test portion taken from the same gives with caustic potash in excess the emerald-green coloration peculiar to the chromium-hydroxid compound. The fluorinated chromium hydroxid is added to water to make a solution containing four per cent. of the hydroxid or in the same proportion to a so lution of I uebracho, sumach, chestnut-oak, divi-divi, ning purposes.

Example: A hide or butt, of'twenty kilo-' grams weight, intended .for ordinary sole leather, is introduced into a vat containing forty kilograms of asolution of four-per-cent. strength of fluorinated chromium hydroxid and left in the solution, being frequently stirred, until test pieces cut off at the thickest parts of the hide show that the tanning process is completed. The hide is then rinsed and drawn through a weak bath of milk of lime, soap, or other alkaline bath in order to bind any free acid present which might have prejudicial efiect in the further treatment of the hide, especially'in the dyeing. The treat ment of the hides by the finorinated chro= mium hydroxid in solution results in the pro duction of a leather which when further treated by the processes usually employed issuitable for the uses to which leather is com- I monly put.

What I claim, and desire to secure by Lettors Patent of the United States, is-

A method of tanning or dressing skins,

hides and the like, comprising the treatment of the same with a fluorin compound of chromium hydroxid.

In testimony whereof I have hereunto set my hand in the presence of two witnesses. FRIEDRICH VALENTINER. Witnesses:

RUDOLPH FRIOKE, OHAs. J. BURT.

c., of the usual strength for tau 

